Abstract
Against the background of safety assessment of welded joints in piping constructions, the welding process is simulated numerically in the present work. The paper focuses on manual multi-pass edge fillet welds at high-pressure pipelines made of steel L485MB (X70). The simulation is based on the finite element method and allows for the prediction of temperature fields and microstructure evolution during welding and cooling. To describe the heat input during welding the double-ellipsoidal Goldak heat source is implemented into the commercial software ABAQUS. To account for different bead shapes the Goldak heat source is modified by projecting it onto the bead shape of each welding pass. The microstructure evolution is analyzed by a phase transformation model based on the calculated transient temperature fields. The ferritic, pearlitic and bainitic transformations are simulated by the Avrami equation. Effects of reheating during multi-pass welding are taken into account. In order to validate the simulation extensive welding experiments are carried out. The experimental observations are presented and compared to the numerical results by means of macrosections and thermocouple measurements.